Disappointed with Scheduling and Communication

I was initially impressed when I enquired about Cartrack and received a callback within a minute — great responsiveness! However, things quickly went downhill. I was told the device would be fitted at 3 PM. When I called at 3:30 PM to follow up, I was informed that the appointment had been moved to 5 PM and that I should have received a call and SMS — neither of which I got. 5 PM came and went with no update. I called again and was told the scheduling department was closed, and that Customer Care would send an email, but I’d only get a response the next day. This lack of communication and follow-through has left me uncertain about continuing with Cartrack. Question: Can I cancel the service before the device is installed?